Process for producing supply stock and supply stock for saw blades or saw belts

ABSTRACT

The invention relates to a process for producing supply stock for saw blades or saw belts with a carrier part and a cutting part made from different materials being metallically bonded to one another by means of welding, whereupon the thickness of the bi-metal or tri-metal bond is adjusted or set and supply stock is formed.  
     In order to avoid longitudinal grooves and material stress in the bonded region of the supply stock, which can develop by milling for the purpose of adjusting an even belt thickness, it is provided according to the invention for at least one surface side of the bonded part to be cut at least locally in the bonded area and for the bulging of the weld seam and/or the welding bead to be removed subsequently to the welding of the parts.

[0001] The invention relates to a process for producing supply stock for saw blades or saw belts with a carrier part and a blade part made from different materials becoming metallically bonded to one another by means of welding, and with the thickness of the bonded or bi-metal part being adjusted or set and the supply stock being formed.

[0002] Additionally, the invention includes supply stock for the production of saw blades or saw belts comprising a carrier part and at least one cutting part, which parts are metallically bonded to one another by means of welding forming, a bi-metal or tri-metal bonded part, and with the supply stock being adjusted in its thickness.

[0003] Due to different wear during use, on the one hand, saw blades or saw belts must be able to compensate high bending, tensile, and transverse strain in the blade part or carrier part and, on the other hand, must be provided with high stability of shape of the cutting edges and/or high abrasion resistance and/or wear resistance of the edge tips.

[0004] It is known to produce saw blades or saw belts from a supply stock comprising different material parts, i.e., a carrier part and/or carrier belt made from a tenacious material and a blade part made from a material that can achieve high hardness and high wear resistance by means of thermal hardening. For producing such a so-called bi-metal or tri-metal belt, a carrier belt and at least one cutting material belt are bonded to one another without any additional material, in most cases using laser welding or electron-beam welding.

[0005] However, the weld joint of the material parts can represent a problematic zone with respect to production technology and metallurgy. On the one hand, a complete welding of the narrow sides of the belts is to be achieved; on the other hand, undesired bulging of the weld seam and/or the formation of a disturbing, raised welding bead is to be avoided. Additionally, the welding bead and/or the bond region formed during welding are provided with lower tenacity and high stability of the material regarding changes in shape.

[0006] In order to avoid weld joint bulges to a large extent, welding technologies have been optimized for that purpose; however, during the complete welding of the narrow sides of the belts, the formation of a convexly protruding welding bead can occur at least on one side.

[0007] It is common in prior art, subsequent to the welding of the carrier part to the blade part, to mill and/or adjust the bonded belt with respect to thickness, which is called dressing by one skilled in the art, thus producing a supply stock for the production of saws not containing any convex or protruding regions on the lateral surfaces, called belt surfaces in the following. However, this measure, though counteracting increased friction between the saw blade and the material to be sawed, has the disadvantage that, on the belt surfaces, the protruding regions of the welding beads are pressed into the supply stock/belt cross section with an increased deformation. Thus, tapering of the material on both sides of the milled volume areas in the belt can occur and longitudinal grooves can be present on both sides of the deformed welding bead in the belt.

[0008] However, these longitudinal groves in the bond region of the two material parts have the disadvantage that, subsequent to the forming of the tooth spaces, the grooves in the tooth region can cause increased tension in the base of the notch, thus presenting the danger of tears arising that may cause the fracture of tooth tips during practical operation of the saw or a shortening of the life of the saw.

[0009] With respect to improving the quality of the supply stock and, ultimately, achieving a high saw quality, the object of the invention is to avoid longitudinal grooves in the bond region of the two material parts of the and/or at the supply stock and to restrain the danger of tears arising from grooves in the longitudinal direction of the belt in the bond region of the material parts.

[0010] This object is attained in a process of the type mentioned at the outset in that, subsequently to welding the parts, at least one side of the surface of the bonded part is worked in a cutting fashion at least locally in the region of the connection and the bulging of the welding seam and/or welding bead is removed.

[0011] The advantages achieved with the invention can essentially be seen in the fact that, in spite of an adjustment of the plane parallelism of the belt, the build-up of mechanical stresses in the same can be minimized, in particular, can be prevented. Therefore, no increased local material tensions caused by the milling of bulging in the welding region are present between the carrier material and the cutting part, which provides improved use characteristics with an extended life span for a saw made from the supply stock.

[0012] Particular advantages regarding the quality of the bond of the parts and regarding the quality of the saw ultimately made from the supply stock is achieved when the weld joint bulging is removed by grinding, in particular polishing.

[0013] However, it may be important and advantageous here for the cutting or the polishing of the bonded part to occur in a direction for removal of the material which is perpendicular or diagonal to the longitudinal direction of the bonded part, and for the tool and the bonded part to be moved relative to one another in the longitudinal direction.

[0014] The quality of the belt surfaces of the supply stock for a saw made from this material can be improved and the friction between the saw blade and the material to be sawed can be reduced in an advantageous manner when subsequent to the cutting of the bonded part, a post milling occurs for the purpose of adjusting or setting the thickness of the supply stock for saws.

[0015] The further object of the invention is achieved by the appropriate supply stock for the production of saw blades or saw belts in that, at least in the bonded region of the carrier part and the cutting part, the surfaces of the supply stock belt are formed without longitudinal ridges. The advantages thus achieved must be considered essentially in that no temperature peaks in the material can occur near the surface during thermal hardening of the saw blade, caused by ridges. Additionally, no tearing initiation points are present so that during the use of the saw the danger of tooth tips fracturing is low.

[0016] The initiation of tears originating from grooves and the breaking off of the tips of cutting parts caused thereby can be avoided to a large extent when at least one side of the surface of the supply stock is provided with a grinding structure or grinding grooves, at least in the bonded region of the parts, which are perpendicular or diagonal to the longitudinal direction of the supply stock.

[0017] Particularly high requirements for the quality of the supply stock can be achieved when additionally, as can be advantageously provided, the supply stock is finally provided with a surface adjustment and/or thickness setting by means of post milling.

[0018] The invention is explained in greater detail using the drawings. They show:

[0019]FIG. 1 to FIG. 3: schematically in cross section, sketches relating to the production of supply stock for saw belts according to the prior art:

[0020]FIG. 1 bonded part

[0021]FIG. 2 milling or adjusting of the bonded materials

[0022]FIG. 3 supply stock

[0023]FIG. 4 to FIG. 7 etching patterns of microsections of the weld joint having an enlargement of 110:1 for

[0024]FIG. 4 welding bead

[0025]FIG. 5 welding bead, partially milled

[0026]FIGS. 6 and 7 supply stock with a welding bead removed by cutting

[0027] In FIG. 1, a bonded part or bi-metal part 1′ is shown schematically. This bonded part 1′ comprises a carrier belt 2 metallically bonded with a blade belt 3 by means of a weld bond 4. The weld bond 4 has bulges 41, 42 of the weld seam on the belt surface, which were formed during welding.

[0028]FIG. 2 shows a weld bond 4, depicted essentially like in FIG. 1, being deformed by the impact of force y, y′ from the rolls 5, 5′. Due to such deformation of the weld seam, called dressing of the bonded part by one skilled in the art, an adjustment to an even thickness of the carrier belt 2, the blade belt 3, and the weld bond 4 occurs as necessary for the supply stock for the production of saws.

[0029]FIG. 3 shows a supply stock 1 subsequent to being leveled by rolls. A weld seam 4 has the same thickness as the carrier belt 2 and a blade part 3. By deforming and/or milling of bulges shown in FIG. 1 and FIG. 2 for achieving an even belt thickness longitudinal grooves 43, 43′, 44, 44′ and material stress develop in the bonded region. Preferably, longitudinal grooves 43, 43′, 44, 44′ form due to transverse stress in the material next to the weld bond. Additionally, milling of bulges 41, 42 lead to mass displacement and the formation of inner stress in the material. Both can lead to a weakening of the bond between the carrier part 2 and the blade part 3 during the production of saws from such supply stock.

[0030]FIG. 4 shows the microsection of a weld bond perpendicular to the longitudinal direction of the bonded part with an enlargement of 110:1. The bulging of the welding bead above the surfaces of the carrier belt and the blade belt is clearly discernible.

[0031] In FIG. 5, a milled bulge is discernible in the microsection, with longitudinal grooves being formed on both of its sides.

[0032] In FIGS. 6 and 7, weld bonds of a supply stock are depicted made using the process according to the invention. Differences in the appearance of the material in the microsection are caused by different etchings and/or etching means. The lack of longitudinal grooves in the supply stock is clearly discernible.

[0033] Experiments have shown that saw blades and saw belts made from supply stock according to the invention have a considerably lower rate of failure caused by tooth fractures. Furthermore, it was shown that improved welding processes resulting in larger bulges and/or welding beads can be used as well because the bulges are ultimately cut off. 

1. Process for producing supply stock for saw blades or saw belts with a carrier part and a blade part made from different materials being metallically bonded to one another by means of welding and subsequently the thickness of the bonded or bi-metal part being adjusted or set and the supply stock being formed, characterized in that subsequent to the welding of the parts at least one surface side of the bonded part is at least locally cut in the bonded region and the bulging of the weld seam and/or the welding bead is removed.
 2. Process according to claim 1, characterized in that the weld seam bulging(s) is (are) removed by grinding, in particular polishing.
 3. Process according to claim 1 or 2, characterized in that the cutting or grinding of the bonded part occurs with a removal direction of the material directed perpendicularly or diagonally to the longitudinal direction of the bonded part, with the tool and the bonded part being moved in the longitudinal direction in relation to one another.
 4. Process according to claims 1 through 3, characterized in that subsequent to the cutting of the bonded part for the purpose of removing the stock, a post milling of the same occurs in order to adjust or set the thickness of the supply stock for saws.
 5. Supply stock for the production of saw blades or saw belts comprising a carrier part and at least one cutting part, which parts are metallically bonded by means of welding, forming a bi-metal or tri-metal bonded part and with the supply stock being adjusted in its thickness, characterized in that at least in the bonded region of the carrier part and the cutting part the surfaces of the supply stock belt are formed without any lateral grooves.
 6. Supply stock according to claim 5, characterized in that at least one surface side of the supply stock is provided, at least in the bonded region of the parts, with a grinded structure or grinded grooves which are perpendicularly or diagonally positioned in relation to the longitudinal direction of the supply stock. 